Which of the following is NOT one of the primary rules for firearm safety?

The principle that a firearm should be the most expensive is not a primary rule for firearm safety. Firearm safety rules are designed to prevent accidents and ensure responsible handling of firearms, regardless of their cost. The primary rules emphasize awareness and control of the firearm’s handling and direction, such as keeping the muzzle pointed in a safe direction to prevent unintentional discharge from harming someone or something.

Additionally, keeping your finger off the trigger until you are ready to shoot is crucial to avoid premature firing and accidents. It ensures that a shooter maintains control and only takes a shot when they are prepared and it is deemed appropriate. Lastly, avoiding placing loaded firearms in a motor vehicle enhances safety by reducing the risk of accidental discharges while driving or in situations where the firearm could be handled unexpectedly.

Thus, the notion of a firearm's cost does not contribute to safety practices; rather, it’s the adherence to fundamental safety rules that is essential for responsible firearm use.